In reply to PaulJepson:
Well it seems that Wild Country have not updated their advice or made any further steps towards offering a re-slinging service:
"Unfortunately, we do not have any facilities capable of carrying out any re-slinging. We are working on this issue in order to be able to provide this kind of service in the future, so please keep an eye on our website for any further development on this matter.
For the time being, we recommend you visit your local climbing store, as they might be able to help you out directly or at least address you towards somebody that carries out the service you are after.
We're sorry we cannot do more for you directly right now.
Please bear in mind that we recommend that all of our technical hardware is retired after 10 years, 5 years for all the soft goods (slings, harnesses etc.)"